This invention relates to power generating systems and methods of introduction of bypass steam into steam surface condensers.
The primary function of steam surface condensers in a power plant application is to condense the turbine exhaust steam. In certain applications such as combined cycle plants, trash to steam plants, etc., the steam surface condenser is required to condense the steam that has bypassed the steam turbine. In the bypass scenario, the steam turbine is usually not functioning. The steam from the steam generating devices bypasses the steam turbine and is admitted to the condenser at a suitable pressure and temperature.
In large rectangular condensers the bypass steam is admitted in a steam dome. Such steam domes have large steam spaces and provide ample space for the bypass steam to expand and dissipate it""s energy.
In cylindrical condensers, however, the steam space adjacent to the tubes is very limited, requiring the bypass steam to expand in confined spaces. The design of dump inlet headers, therefore, is very critical. During expansion, the bypass steam must not cause any damage to the condenser shell internals. The bypass steam must be permitted flow into the all parts of the tube bundle and condense efficiently.
In cylindrical steam surface condensers, the bypass steam is usually admitted in the confined space between the shell of the condenser and the tubes, or in the steam inlet. If admitted in the confined space between the shell and the tubes, the expanding bypass steam tends to cause damage to the tubes and the shell. If admitted in the steam inlet, the bypass header tends to block the flow of incoming turbine exhaust steam, thereby affecting the performance of the condenser. In each of the conventional systems for admission, the shell internals are exposed to the damaging effects of expanding bypass steam. Repairing of replacing the damaged shell internals is a very time consuming and expensive proposition.
It is an object of the present invention to avoid the damaging effect of introducing bypass steam to cylindrical steam surface condensers in power generating steam turbine systems.
It is another object of the invention to introduce bypass steam to cylindrical steam surface condensers with greatly reduced damage to the condensing tubes and other shell internal components.
A further object is to introduce bypass steam to condensers with reduced noise.
These objects, and others which will become apparent from the following disclosure and drawings, are achieved by the present invention which comprises in one aspect a system for introducing bypass steam to a cylindrical steam surface condenser, the condenser having condensing tubes and a condenser shell, the condenser shell with a opening to accept bypass steam, the system comprising a hat-like steam admission chamber external to the condenser shell, the admission chamber adapted to fit the opening in the condenser shell, the admission chamber including a header having orifices arranged within the admission chamber, the system also comprising dummy rods or tubes located above the tube between the condensing tubes and the opening.
In another aspect, the invention comprises method of introducing bypass steam to a cylindrical steam surface condenser having a condenser shell and condensing tubes comprising providing an opening in the condenser shell and a hat-like steam admission chamber external to the circumference of the condenser shell; securing the admission chamber to the opening in the condenser shell, the admission chamber including a header having orifices arranged within the admission chamber; and providing dummy rods or tubes arranged within the circumference of the condenser between the condensing tubes and the opening to buffer the impact of the bypass steam released through the orifices prior to the bypass steam reaching the condensing tubes.
It is preferred to construct the bypass inlet header of stainless steel. The header can be a single steam inlet with orifices for release of the steam into the admission chamber, or can be two or more steam inlets with orifices which can be arranged one within the other. In embodiments of header systems with two steam inlets, a low pressure inlet can be inside a high pressure inlet.
It is preferred to construct the admission chamber of a large lower cylinder and a large upper cylinder, with the lower cylinder welded to the opening, and the upper cylinder welded to the lower cylinder. Alternatively the upper cylinder can be directly welded to the opening in the condenser. The upper cylinder can have a cover with an opening through which the header is arranged.
The hat-like steam admission chamber is preferably covered with a suitable material to reduce the noise emanating from the expanding steam.